Air circulating footbed and method thereof

ABSTRACT

An air circulating footbed adapted for insertion into a shoe including first and second layers of material shaped and attached to each other so as to define at least two cavities therebetween, the first cavity being disposed generally in the forefoot region of a shoe and the second cavity being disposed generally in the heel region of a shoe, the first and second cavities being in fluid communication with each other whereby foot pressure exerted by a wearer&#39;s foot in the forefoot and heel regions of the footbed during a wearer&#39;s walking or running gait will circulate air flow back and forth between the at least two cavities. The cavities may also include low density polyurethane (PU) foam in the density range of 0.20 to 0.50 pounds per cubic foot.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Applications Ser. No. 61/173,955, filed Apr. 29, 2009, entitledAIR CIRCULATING FOOTBED AND METHOD THEREOF, which application is herebyincorporated by reference to the extent permitted by law.

BACKGROUND OF THE INVENTION

The present invention relates generally to the construction of a shoeand the manufacture thereof and, more particularly, to a footbed or socklining with an improved air cushioning system to enhance the comfort ofa user's foot.

The footwear industry has seen numerous design features introduced inorder to enhance the comfort and/or performance of a shoe on the foot ofthe wearer. Many of the technological advances have occurred in thesole, particularly the midsole. In most footwear, the midsole oftenprovides both protective cushioning and a stable platform for the user'sfoot. In an effort to provide improved performance, it is oftendesirable to vary the support characteristics of the sole from oneregion to another. A wide variety of soles have been developed toprovide variable support over the foot. Although a marked improvementover conventional uniform sole constructions has occurred over theyears, there remains a need for a footbed construction that can beadapted to accommodate the mechanical stresses arising on a wearer'sfoot during different kinds of activities and which provides a highdegree of functionality and wearing comfort.

A shoe is generally composed of an upper connected to a sole. The soleis generally composed of an outsole, a midsole and an insole disposed ontop of the midsole. A footbed is disposed within the shoe on top of theinsole. The footbed lies adjacent to the bottom surface of a user's footwhen the shoe is worn. Because the footbed is in direct contact with auser's foot, it is important that the footbed be anatomically conformedto the user's foot and help the foot remain cool and comfortable wheninside the shoe.

It has been known to provide a footwear sole to cushion the impact of aperson's foot with a supporting surface. The concept of shock absorptionby transfer of fluid from the heel to the ball or forward portion of theuser's foot has been known as illustrated in U.S. Pat. No. 4,458,430 toPeterson. The Peterson patent describes a cushioning device havingcushions disposed beneath the heel and front transverse arch of thefoot. The cushions are filled with a fluid. A major deficiency of thePeterson device is the “bulging effect” when the Peterson device is madein the form of footbed or sockliner. Particularly, the Paterson deviceleads to “bottoming out” of heavily loaded chamber and the simultaneousballooning of unloaded chamber, creates a very uncomfortable bulgewithin the unloaded chamber and causes discomfort of the foot portioncontacting the unloaded chamber due to the uneven surface of the footbedor sockliner. Further, when one of the cushions is heavily compressed,the foot portion contacting the compressed chamber could feel someimpact due to lack of threshold level of support as fluid is forced fromthe compressed chamber to the expanding one. Furthermore, extremely highlevel of quality control in some manufacturing environment is needed tokeep all the air cavities at a consistent air pressure.

The demands for comfort in other athletic events has resulted in the useof the inflatable bladders in various types of athletic footwear. Thereare presently available athletic shoes incorporating an air pump, suchas depicted within U.S. Pat. No. 5,074,765, to inflate air bladderslocated within the sole of the shoe, or alternatively, bladders locatedin portions of the midsole or outsole of the athletic shoe. However, theprior art footwear utilizing bladders have made them costly and timeconsuming to manufacture.

It is a general object of this invention to provide an improved shoesole structure which avoids the drawbacks of the known constructions.Still another object of the present invention is to provide a shoe solestructure which is durable in construction and inexpensive tomanufacture, and which affords additional advantages over the known shoesole constructions. The present devices attempt to enhance cushioningand energy return by transferring a fluid between the area of impact andanother area of the device and to keep the threshold level of support byadding low density foam insert to air cavities. The basic concept of thepresent devices is to have cushions containing foam and air disposedadjacent the heel or forefoot areas of a shoe which transfer air to theother of the heel or forefoot areas.

Thus, it would be desirable to provide an improved footbed which iscapable of providing damping and support for the foot.

It would also be desirable to provide a footbed for a shoe which iscapable of circulating cushioning air through the interior of the shoe.

SUMMARY OF THE INVENTION

The present invention relates to an improved footbed including multiplecavities capable of holding air and foam, and an interconnecting channelcapable of circulating air between the cavities. The term footbed refersto a layer of material or the like placed over the entire insole toprotect the foot from seams or other constructional workings on theinside of the shoe. The sole of a shoe is generally comprised of anoutsole, a midsole, and an insole. A conventional footbed may be placedinside the shoe above the insole. The present invention is directed to afootbed construction having enhanced air cushioning capability.

In one aspect of the present invention, an air circulating footbed isprovided which includes a multi-layered construction enabling it toprovide the above-described objectives. The footbed includes two mainlayers and an air circulating system formed therebetween. A top layer,sometimes called a sock liner, provides a layer between the bottomsurface of a wearer's foot and the footbed. The top layer has an uppersurface and a lower surface, the top layer providing a sock-contactingsurface as well as protection for the footbed and an area to display themanufacturer's information. Beneath the top layer, a bottom layer ofmolded ethyl vinyl acetate (EVA) is attached. The bottom surface of thetop layer forms two concave surfaces, one located in the area of theforefoot and the other located in the heel area. These two concavesurfaces, when positioned adjacent the bottom layer, form two cavitiesenclosed by the top and bottom layers. The two cavities are connectedtogether by an interconnecting air transfer channel located in the archarea, the interconnecting air channel extending between the twocavities. The bottom layer extends from the heel to the forefoot area,namely, in the area corresponding to the ball of a wearer's foot. Thefront end portion of the bottom layer is securely affixed to the lowersurface of the top layer at a location corresponding to the ball of thefoot and the rear end portion of the bottom layer is securely affixed tothe lower surface of the top layer in the vicinity of the heel area. Themethod of attaching the top layer of the footbed to the bottom layer ofthe footbed, thereby closing the cavities, can be by adhesion or by heatsealing.

The air circulating system of the present invention includes a frontcavity, a rear cavity and an interconnecting air transfer channel Theinterconnecting air transfer channel is designed to optimize circulationof air between the two cavities. The front cavity formed at the forefootarea is in direct air communication with the rear cavity formed at theheel area through the interconnecting air transfer channel formed at thearch area in the middle section of the footbed. The flow of air from onecavity to the other cavity is accomplished by pressure from the wearer'sfoot during various parts of a wearer's walking or running gait.

The present cavities are at least partially filled with foam and airfunction as a pumping and cushioning device. In one embodiment, eachcavity is substantially filled with suitable low-density polymer foaminsert, such as polyurethane, which is resiliently compressible under anapplied load to attenuate ground reaction forces and absorb energy. Inanother embodiment, at least one cavity is partially filled withsuitable low-density polymer foam insert. In a preferred embodiment, thefoam insert is not bonded to the inner surface of the cavities that holdsome air between the inner surface of the cavities and the outer surfaceof the foam insert. Each of the front and rear cavities form a foamholding volume which is vertically moved by the force or pressureapplied in the forefoot and heel areas of the top layer respectively.When pressure is applied to the forefoot area during toe-off, air movesrearward from the front cavity to the rear cavity. When pressure isapplied to the heel area during heel strike, air moves forward from therear cavity to the front cavity. The cavities are formed in order tomaximize the amount of air trapped within such cavities and the amountof air pushed through the interconnecting air transfer channel. Once thebottom layer is affixed to the top layer, the air enclosed between thetwo layers will be sealed such that no air enters the enclosed area andno air can escape therefrom.

It is an object of the present invention to provide an air-circulatingfootbed which provides enhanced cushioning by adding ambient air as wellas low density foam insert to the cavities.

It is a further object of the present invention to provide an improvedfootbed which is simple to manufacture and which can be utilized in anystandard shoe.

Specific advantages and features of the present system will be apparentfrom the accompanying drawings and the description of severalillustrative embodiments of the present invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan form view of one embodiment of a footbedconstructed in accordance with the teachings of the present invention.

FIG. 2 is a side cross-sectional view of the footbed of FIG. 1 takenonly line 2-2 of FIG. 1.

FIG. 3A is a fragmentary cross-sectional view of the present footbedwithout showing foam insert within the cavities, taken along line 3-3 ofFIG. 1.

FIG. 3B is a fragmentary cross-sectional view of the present footbedshowing foam insert within the cavities, taken along line 3-3 of FIG. 1.

FIG. 4 is the side cross-sectional view of FIG. 2 showing a user's footpositioned on the footbed.

It should be understood that the drawings are not necessarily to scaleand that the embodiments disclosed herein are sometimes illustrated byfragmentary views. In certain instances, details which are not necessaryfor an understanding of the present invention or which render otherdetails difficult to perceive may have been omitted. It should also beunderstood that the invention is not necessarily limited to theparticular embodiments illustrated herein. Like numbers utilizedthroughout the various figures designate like or similar parts orstructure.

DETAILED DESCRIPTION

Referring now to the drawings and, in particular, FIGS. 1-4, a firstembodiment of a new and improved removable shoe footbed having an aircirculating system embodying the principles and concepts of the presentinvention and generally designated by the reference numeral 10 will bedescribed.

A shoe generally includes an upper and a sole assembly that is affixedto the upper. The sole assembly includes an insole, a midsole, and anouter sole, each having a peripheral shape designed to conform to theshape of a wearer's foot. The shoe may also include a footbed that isremovably fitted into the shoe upper on top of the sole assembly. Tofacilitate disclosure of the present invention, reference will be madeto various general areas of the foot, such as the heel, arch andforefoot areas. When used to refer to locations on the various solecomponents, these terms should be interpreted to include those areas ofthe footbed that are disposed generally (and not necessarily directly)beneath the corresponding elements of the foot. It should be understood,however, that the boundaries between the heel, arch and forefoot areasare not precise and that these terms should be interpreted loosely andwith a great deal of flexibility.

A footbed 10, as shown generally in FIGS. 1 and 2, has a medial side anda lateral side. Footbed 10 also has a toe end 12 and a heel end 14. Thelength and width of footbed 10 are completely dependent upon the size ofshoe into which footbed 10 will be placed. Footbed 10 is shown in FIGS.2-4 to comprise two main layers. A top layer 16, sometimes called a sockliner, provides a layer between the wearer's foot and the footbed 10 andmay include multiple layers. Top layer 16 has an upper surface 18 and alower surface 20. Upper surface 18 of the top layer 16 also defines theupper surface of the footbed 10. The specific material of the top layer16 may be chosen depending on the nature and type of shoe in which itwill be used. Top layer 16 may be made from a variety of materialsincluding, but not limited to, grain leather, suede leather, PVC coatedmaterials, or any other thin synthetic or natural material. The materialselected will be determined by the type of footwear into which footbed10 is intended to be placed. Top layer 16 is used to provide generalprotection to the footbed 10 from normal wear and tear. The height orthickness of the top layer 16 may be raised at the arch and forefootareas to support the foot in a conforming fashion. Lying underneath toplayer 16 and providing a seal to circulating air is a bottom layer 22.The footbed includes an air circulating system 24 between the top layer16 and the bottom layer 22.

Referring now to FIGS. 2-4, the bottom layer 22 has an upper surface anda lower surface. The upper surface of bottom layer 22 traps or enclosesair within the air circulating system 24 formed between the top andbottom layers 16 and 22. Bottom layer 22 extends from the heel area tothe forefoot area as best seen in FIGS. 2 and 4. In the embodimentillustrated, the bottom layer 22 extends from the heel area of footbed10 to a location corresponding to about two-thirds the length of footbed10. Although bottom layer 22 may extend to other portions of thefootbed, or the entire length of footbed 10, it is preferable thatbottom layer 22 extend only to the location corresponding to the ball ofthe foot for increased forefoot flexibility. The front end portion 26 ofthe bottom layer 22 is securely affixed to the lower portion of the toplayer 16 at a location corresponding generally to the ball of the foot.The rear end portion 28 of the bottom layer 22 is securely affixed tothe lower portion of the top layer 16 generally at the heel area. Theheight or thickness of the bottom layer 22 may be uniform across theentire length of the bottom layer 22.

The air circulating system 24 includes a front cavity 30, a rear cavity32 and an interconnecting air transfer channel 34. The material of thetop layer 16 is molded by conventional molding techniques, such asinjection molding, to form two concave surfaces 19 and 21 in theforefoot and heel areas respectively, which concave surfaces whenenclosed by the bottom layer 22, form cavities 30 and 32 as well as theinterconnecting air transfer channel 34 at the arch area between the twocavities. The top and bottom layers 16 and 20, when mated and attachedto each other, form and define the front and rear cavities 30 and 32respectively and the interconnecting channel 34. The upper surface ofbottom layer 22 traps or encloses air within the air circulating system24 formed between the top and bottom layers 16 and 22. In a preferredembodiment, the cavities 30 and 32 are filled with suitable low-densitypolymer foam insert 36 and 38, such as polyurethane, which isresiliently compressible under an applied load to attenuate groundreaction forces and absorb energy. Each of the front and rear cavitiesform a foam holding volume which is vertically moved by the force orpressure applied in the forefoot and heel areas of the top layerrespectively. The quantity of foam insert 36 and 38 placed in the moldcavities is sufficient to substantially fill the cavity when it isclosed. During walking, running, or other ambulatory activities, thecavity and the foam insert therein are compressed between the foot andthe ground, thereby attenuating ground reaction forces and absorbingenergy.

While at least some portions of the cavities 30 and 32 are filled withthe foam insert 36 and 38, the remaining portion of each cavity 30 and32 will be filled with air. In one embodiment, each cavity 30 and 32 issubstantially filled with suitable low-density polymer foam insert 36and 38, such as polyurethane, which is resiliently compressible under anapplied load to attenuate ground reaction forces and absorb energy. Inanother embodiment, at least one cavity 30 and 32 is partially filledwith suitable low-density polymer foam insert 36 and 38. In a preferredembodiment, the foam insert 36 and 38 is not bonded to the inner surfaceof the cavities 30 and 32 that hold some air between the inner surfaceof the cavities and the outer surface of the foam insert 36 and 38.Further, the foam material is resiliently compressible, in part, due tothe inclusion of a plurality of open or closed microcells that define aninner volume substantially displaced by air. As the cavity 30 and 32 iscompressed, the air enclosed in the cavity 30 and 32 is transferred tothe other cavity through the interconnecting air transfer channel 34such that the partially or substantially filled cavities 30 and 32enable excess air to be squeezed out of the compressed cavity 30 and 32.Air transfer channel 34 is designed to optimize circulation of airbetween the two cavities 30 and 32. The front cavity 30 formed in thevicinity of the forefoot area is in direct air communication with therear cavity 32 formed in the vicinity of the heel area through theinterconnecting air transfer channel 34 which is formed in the vicinityof the arch area towards the middle section of the footbed 10. Theheight or depth of the cavities 30 and 32 and the air transfer channel34 may vary depending upon the particular application and the type ofshoe involved. In a preferred embodiment, the front and rear cavities30, 32 may have a height in the range of approximately 5-8 mm, while theinterconnecting air transfer channel 34 may have a height in the rangeof approximately 3-5 mm. The flow of air from one cavity to the othercavity is accomplished by pressure from the wearer's foot during variousparts of a user's walking or running gait. Upon removal of thecompressive force caused by the foot and the ground, the originalconfiguration of the cavity is restored by the difference of the airpressure between the cavities and recovery of the foam insert to itsoriginal shape.

In order to fully appreciate the present invention, implementation ofthe footbed 10 utilized in accordance with the present invention willnow be described. In use, footbed 10 is placed inside a conventionalshoe with bottom layer 22 pressed in face-to-face contact with theinsole of the shoe. As shown in FIGS. 2 and 4, when employing thecavities 30 and 32 as a pumping device, the heel of the wearer's footduring heel strikes exerts or causes sufficient pressure to be appliedto the rear cavity 32 with significant impact to force the air trappedwithin cavity 32 to move forward through the transfer channel 34 to thefront cavity 30. In similar fashion, the forefoot of a wearer's footduring toe-off exerts or causes sufficient pressure to be applied to thefront cavity 30 with significant impact to force the air trapped withincavity 30 to move rearward through the channel 34 to the rear cavity 32.Each of the front and rear cavities 30 and 32 forms an area which isvertically moved by the force or pressure applied in the forefoot andheel areas of the footbed 10. The cavities are formed by and between thetop and bottom layers 16 and 22 of the footbed 10 in order to maximizethe amount of air trapped within such cavities and the amount of airpushed through the interconnecting air transfer channel 34. During thewearer's walking or running gait, the increased pressure exerted by theball of the wearer's foot on the front cavity 30 will create sufficientpressure to push air from the front cavity 30 to the rear cavity 32, andthe increased pressure exerted by the heel of the user's foot on therear cavity 32 will create sufficient pressure to push air from the rearcavity 32 to the front cavity 30 thus providing the ball and heel of thewearer's foot with repeated blasts of air. Once the bottom layer 22 isaffixed to the top layer 16, the air enclosed between the layers of thefootbed 10 will be sealed and trapped so that no air can enter or exitthe enclosed area, namely, cavities 30 and 32 and channel 34.

The precise composition of the bottom layer 22 is not critical so longas it meets the physical and performance criteria set out above. The toplayer 16 may be comprised of a conventional foam plastic material with afabric sock liner integrally secured to the upper surface of the toplayer 16. The bottom layer 22 is preferably made from a firm,compressible, lightweight, and moldable material such as ethyl vinylacetate (EVA). A number of different polymers may be compounded andformed in a manner to meet the necessary criteria but EVA is preferred.The density and hardness of a suitable polymer foam insert may varywithin the scope of the present invention. In a preferred embodiment,the low density foam insert is a polyurethane (PU) foam with a densitybetween 0.20 and 0.50 pounds per cubic foot.

The two layers 16 and 22 of the footbed 10 perform very separate anddistinct functions. The bottom layer 22 functions to provide aconforming interface between the shoe and a wearer's foot. Cushioning ofthe foot is provided primarily by the top layer 16 which functions as apumping device for circulating air between the cavities 30 and 32 andalso acts to absorb lateral movements of the foot relative to the shoe.The provision of the air circulating system 24 within the footbed 10prevents the top layer 16 from bottoming out or reaching anuncompressible state.

The method of attaching the top layer of the footbed to the bottom layerof the footbed, thereby closing the cavities, can be by adhesion or byheat sealing. A surface roughing treatment which can be formed byroughening the surface is often necessary prior to application of anadhesive, or by high frequency, sonic or conductive heat sealing. Asuitable heat sealing apparatus applies a current, whereby localisedresistance heating causes the thermoplastic materials to melt locallyand to at least partially fuse to join the thermoplastic materials.Preferably, the materials become fused when they are cooled, to form abond.

Although FIGS. 1-4 illustrate only a pair of cavities 30 and 32, it isalso recognized and anticipated that the present footbed 10 couldinclude any plurality of cavities interconnected by any plurality of airtransfer channels such as air channel 34. In this regard, some or all ofthe cavities could be interconnected by the transfer channels, or groupsof the cavities could be interconnected by certain air transferchannels. Further, although FIGS. 1-4 illustrate only substantiallyfilled or unfilled cavities 30 and 32, it is also recognized andanticipated that the present footbed 10 could include a partially filledcavities. Other cavity arrangements and interconnection schemes are alsoenvisioned.

Thus, there has been shown and described several embodiments of a novelinvention. As is evident from the foregoing description, certain aspectsof the present invention are not limited by the particular details ofthe examples illustrated herein, and it is therefore contemplated thatother modifications and applications, or equivalents thereof, will occurto those skilled in the art. The terms “having” and “including” andsimilar terms as used in the foregoing specification are used in thesense of “optional” or “may include” and not as “required”. Manychanges, modifications, variations and other uses and applications ofthe present invention will, however, become apparent to those skilled inthe art after considering this specification and the accompanyingdrawings. All such changes, modifications, variations and other uses andapplications which do not depart from the spirit and scope of theinvention are deemed to be covered by the invention which is limitedonly by the claims which follow.

1. A footbed adapted to be removably inserted into a shoe comprising: afirst layer having an upper surface and a lower surface; a second layerhaving an upper surface and a lower surface, said second layer beingattached to said first layer so as to define a sealed air circulatingarea therebetween; said air circulating area including: a first cavitydisposed at a location corresponding to a location where a forefoot of awearer's foot would sit on said footbed; a first low density foam insertdisposed within the first cavity; a second cavity disposed at a locationcorresponding to a location where a heel of a wearer's foot would sit onsaid footbed; a second low density foam insert disposed within thesecond cavity; and said second cavity being in fluid communication withsaid first cavity for allowing air to circulate between said first andsecond cavities.
 2. The footbed of claim 1 wherein said air circulatingarea comprises an interconnecting air transfer channel disposed betweensaid first and second cavities for allowing air to communicate betweensaid first cavity and second cavity.
 3. The footbed of claim 2 whereinthe interconnecting air transfer channel has a height in the range ofabout 3-5 mm.
 4. The footbed of claim 1 wherein each of said first andsecond cavities has a height in the range of about 5-8 mm.
 5. Thefootbed of claim 1 wherein said first and second low density foaminserts comprise a polyurethane (PU) foam with a density between 0.20and 0.50 pounds per cubic foot.
 6. The footbed of claim 1 wherein atleast one of said first and second cavities is sealed in fluid-proofmanner by a heat sealing method.
 7. The footbed of claim 1 wherein saidfirst and second cavities are substantially filled with said first andsecond low density foam inserts.
 8. The footbed of claim 1 wherein thevolume of said first low density foam insert is less than the volume ofsaid first cavity.
 9. The footbed of claim 1 wherein the second layer isformed of ethyl vinyl acetate (EVA).
 10. A footbed adapted to beremovably inserted into a shoe, said footbed having a forefoot regionand a heel region, said footbed comprising: a first layer having anupper surface and a lower surface, said lower surface defining at leasttwo concave surfaces formed therein; a second layer having an uppersurface and a lower surface, said second layer being attached to saidfirst layer so as to define at least two cavities therebetween, whereina low density foam insert is disposed within each of said at least twocavities; said first cavity being disposed at a location correspondinggenerally to the forefoot region and being defined by one of saidconcave surfaces and the upper surface of said second layer; said secondcavity being disposed at a location corresponding generally to the heelregion and being defined by one of said concave surfaces and the uppersurface of said second layer; and an interconnecting channel disposedbetween said first and second cavities for allowing air to communicatebetween said first cavity and second cavity; whereby foot pressureexerted on the forefoot region and the heel region of the footbed willcirculate air between said first and second cavities through saidinterconnecting channel.
 11. The footbed of claim 10 including aplurality of cavities and a plurality of interconnecting channelsdisposed between said first and second layers.
 12. The footbed of claim10 wherein the interconnecting air transfer channel has a height in therange of about 3-5 mm.
 13. The footbed of claim 10 wherein each of saidfirst and second cavities has a height in the range of about 5-8 mm. 14.The footbed of claim 10 wherein said first and second low density foaminserts comprise a polyurethane (PU) foam with a density between 0.20and 0.50 pounds per cubic foot.
 15. The footbed of claim 10 wherein atleast one of said first and second cavities is sealed in fluid-proofmanner by a heat sealing method.
 16. The footbed of claim 10 whereinsaid first and second cavities are substantially filled with said firstand second low density foam inserts.
 17. The footbed of claim 10 whereinthe volume of said first low density foam insert is less than the volumeof said first cavity.
 18. The footbed of claim 10 wherein the secondlayer is formed of ethyl vinyl acetate (EVA).